The invention relates to a separating device for large, preferably horizontally orientated ball mills or agitator ball mills. The ball mill is a device for the coarse, fine and extremely fine size-reduction or homogenisation of grinding stock. It comprises a grinding chamber which is caused to rotate and in which grinding stock is size-reduced by grinding bodies. Ball mills usually comprise an approximately circular-cylindrical grinding container mounted horizontally rotating. The mills are filled through a central opening at an end wall. The output is dependent on the design and takes place for example via slots in the grinding chamber wall at the end of the mill, wherein the grinding bodies are held back by a separating device.
A special form of the ball mill is the agitator ball mill. Agitator ball mills comprise a vertically or horizontally disposed, usually approximately cylindrical grinding container, which is filled 70-90% with grinding bodies. The grinding chamber is usually stationary, non-rotating in the case of agitator ball mills. An agitator with suitable agitator elements provides for the intensive motion of the grinding bodies. The grinding stock suspension is continuously pumped through the grinding chamber. The suspended solids are size-reduced or dispersed by impact or shearing forces between the grinding bodies. The separation of grinding stock and grinding bodies takes place by means of a suitable separating device at the exit from the mill.
Such a separating device for holding back the grinding bodies usually comprises a sieve, which only allows the passage of the ground product. The sieve can be constituted either rotating with the shaft or can be disposed statically and is disposed in the grinding container in the outlet region for the treated product.
For example, dynamic separating devices for agitator ball mills are known, which are constituted such that a gap is created between a stator fastened to the fastened part of the agitator ball mill and a rotor connected to the rotating part of the agitator ball mill, through which gap only the ground stock can pass. The problem with such separating devices is that the grinding balls separated from the stock or contained in it collect in the edge region of the rotor and are moved together with the rotor, as a result of which rapid wear of the stator and rotor is caused.
DE 4412408 A1 describes an agitator ball mill with grinding bodies. A standard separating device is disposed upstream of the grinding stock outlet. Upstream of said separating device is a pre-grading disc, which preferably conveys the grinding bodies entering into its sphere of action radially outwards. The pre-grading disc is a component of a rotating cage for the most part surrounding the outlet body. As a result of the rotation of the cage, a radial inflow of grinding stock and grinding bodies to the outlet body is for the most part prevented. The separating device is thus largely removed from the impact of the grinding bodies, as a result of which the wear on the separating device can be reduced. Furthermore, the throughput of the agitator mill can be increased considerably.
DD 153331 A1 describes an agitator ball mill for the continuous size-reduction and dispersion of liquid-solid mixtures, which is provided with a separating device. A grinding body build-up in front of the separating sieve is avoided with the agitator ball mill and the entire sieve and area is covered by the grinding body/grinding stock movement. Furthermore, a replacement of the separating sieve can be made without emptying the grinding container. The separating device comprises a flat sieve and is disposed horizontally parallel to the agitator shaft axis at the highest point, at the end of the grinding chamber in the lid of the grinding container constituted as a sieve housing. The separating device is covered by a grinding stock collecting hood equipped with an outlet connecting piece directed obliquely upwards.
DE 19830960 A1 describes a separating device for an agitator ball mill with a sieve, wherein the sieve comprises varying sieve gaps. In particular, the separating device can be present in a first operating position, in which the elements limiting the sieve gap are held at a first spacing by at least partially non-elastic spacers. In a cleaning position, the elements assume a second spacing, which is larger than the first spacing, so that blockages can easily be removed from the sieve gap.
DE 102007012526 A1 shows a further separating device for grinding bodies of agitator ball mills. DE 102010053484 A1 shows an agitator ball mill with a separating device comprising at least two components. A first component is the separating device and a second component is a dynamic element for generating a material flow.
An object of the present invention is to provide a separating device for a ball mill, in particular for an agitator ball mill, said separating device being able to be installed in a straightforward manner and, if need be, capable of being repaired quickly or replaced in part or completely.
The above problems are solved by a separating device for a ball mill or agitator ball mill as well as a ball mill or agitator ball mill with a separating device according to the invention.